The Griots Garage multi-fluid extractor is an example of a tool that certainly seems amazingly useful and convenient. If you haven't seen it before, the concept is that a semi rigid tube is inserted into the dip stick. A vacuum is generated in the cylinder which then pulls the fluid out like a straw sucking up a particularly disgusting milkeshake.

Here's my question: will this extractor drain at least as much oil from a 2004 Subaru Impreza WRX as I would remove by opening the drain plug?

It's not clear from the geometry of the dipstick hole that the tube will be able to reach low enough and the right angle turn at the bottom is too tight to further insert it.

Follow-up: would it be better to jack up the rear of the car to push the oil further forward in the sump to aid access to the extractor?

3 Answers
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This concept works surprisingly well on some engines. As you have mentioned, the issue is whether the dipstick tube allows full access to the sump.

It's unclear from this diagram whether the tube would reach down into the sump. It's also unclear if the tube would run into a baffle or the pickup tube instead of going all the way to the bottom of the sump. To really and truly know for sure on a specific vehicle, I think you'd just have to try it and then pull the plug to see what's left.

In this case, I don't think lifting the back will do much, the design is already leaving the oil no choice but to go into the sump.

If you do try this, get the engine oil really hot so the extractor can suck it with ease, otherwise you'll be waiting all day. This is one nice part about an extractor, that hot oil isn't splashing all over you as you pull the drain plug.

nice picture - that illustrates the double-whammy: the dipstick tube has a tight turn and the drain plug is actually not at the lowest point on the sump.
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Bob Cross♦Mar 8 '11 at 19:36

The drain plug portion of the picture may be a little misleading, I think it is pretty much at the bottom of the sump. Also, the tube for the extractor should be flexible enough to make it past the bend in the dipstick tube. I'm more worried about the extractor tube once it gets into the sump area.
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S_NilesMar 9 '11 at 0:02

I have one of these. Inserting the suction hose into the dipstick tube didn't allow me to remove even half of the oil (the container is marked to show the level of the contents, though it's hard to read except in bright sunlight).

However, there is an easy solution! Measure the dipstick tube diameter and go to your parts shop for a suction hose with a matching interior diameter (specify one that won't melt at 250*F). Put a touch of oil on the outside of the dipstick tube, as lubricant, and slide the new hose over the outside of the dipstick tube. When you start pumping, the suction will draw the oil up out of the engine. Using this technique I have been able to extract 4.25 quarts from my 4.5 qt engine, which is as much as I get by opening the drain bolt.

Some problems with the device:

The suction hose does not thread into the vacuum chamber, causing it to lose vacuum pretty easily, and occasionally pop off completely. This is probably the biggest flaw.

You have to pump almost constantly to extract the oil if the device is placed above the sump.

Cleanup is a PITA.

Still, I use the thing. The first time I used it, it was the easiest oil change I ever did, and each time is just a bit easier. It is also much easier to dispose of the used oil this way (I just drive the entire device to a local Jiffy Lube and pour it into their waste barrel, wipe it down with newspaper and store it in a moving crate that I prepped).

Some tips:

The hose pops off of the chamber pretty easily. I affix it with tape now, as once it popped off mid use, making a huge mess.

There will be a film of oil on the outside of the dipstick tube once you remove the suction hose. Have some newspaper ready.

If you can get the top of the chamber lower than the sump, you'll be able to set up a siphon. Slow but easy.

The oil has to be hot, which you know, but not so hot that it melts the hose.

Get a large bag or box to store the thing in, and line it with oil-absorbing mats (3M "HiSorb" (or something like that) mats are cheap and work great). Before you start :)

If I could go back in time, I wouldn't have spent the money on this. It's good, but even better would be something set up on your drill, like this DIY pump, so you don't need to extract it all manually.

If you have access to air you can use a Vacula, it's fast and easy. Uses air pressure to create the vacuum. I use it for overfills, fluid exchanges, brake bleeding. I have had mine for more than 10 years without any problems.